A well known juice extractor design is disclosed in U.S. Pat. No. 2,649,730 to Hait, and assigned to the present assignee, the disclosure which is hereby incorporated by reference in its entirety. In this type of vertically arranged juice extractor, upper and lower cups support a fruit, vegetable or similar product. The sides of both upper and lower cups have fingers that intermesh and interdigitate together. The upper cup descends into the lower cup against the fruit or vegetable and is pressed against a circular, lower cutter positioned at the top of a strainer tube adjacent the lower cup and an upper cutter positioned in the upper cup. Plugs are cut into the top and bottom portions of the fruit or vegetable as the interdigitating fingers of the two cups mesh together. Inner portions of the fruit, such as the pulp and juice, are forced down into the strainer tube positioned within a manifold. An orifice tube moves upward in the strainer tube and applies pressure into the internal portion of the strainer tube to separate juice and pulp within the strainer tube. Any juice and juice sacks flow through holes of the strainer tube into a juice manifold. Those internal portions of the fruit having particle sizes larger than the holes in the strainer tube are forced through a discharge opening in the orifice tube and then discharged.
In one type of orifice tube, the internal profile of the orifice tube at the first end engaging the fruit includes a taper (bevel), which wears because of the normal abrasion created by engaging the first end with the fruit or vegetable. This internal wear on the orifice tube at its first end can reduce the yield after a period of time. Typically, the tube end wears in a conical fashion, rounding the corners at its internal diameter as it wears. Testing of various orifice tubes in different stages of wear during extractor operation has established that the wearing of the corners has a significant impact on yield.
Orifice tube inserts, known as restrictors, have long been used commercially to restrict access through the orifice tube and increase pressure within the strainer tube during extractor operation. The restrictors are positioned at a medial portion in the orifice tube, but do not extend to the first end that engages the fruit or vegetable. As a result, restrictors have not protected the first end (or entrance) of the orifice tube against wear. These restrictors generally have not been manufactured from a hardened material.
Window-type orifice tubes, such as disclosed in U.S. Pat. No. 3,236,175 and published U.S. patent application Ser. No. US-2002-0166465-A1, the disclosures which are hereby incorporated by reference in their entirety, use “windows” formed in the orifice tube to engage the fruit or vegetable and enhance juice recovery. In the published '465 patent application, a two-piece orifice tube has a screw-in, hardened window portion. The orifice tube described in the '175 patent is stainless steel with an outer plastic sleeve. Some commercial improvements to an orifice tube coat the external surface of the tube with a stellite alloy and machine the tube after coating it to increase wear resistance on the external surface.
Although these prior art restrictors, stellite surfaces, two-piece orifice tubes and other structures provide some advantages depending on the extractor application, for a standard orifice tube having a small taper (bevel) at the entrance end, wear occurs, decreasing yield.